I just put on a Cosworth header and flex. I have a stock exhaust and it sounds a little deeper. But when i floor it, it sounds like the is an exhaust leak. You know like a sourda ticking sound. But I bolts are tight as all get out, I tried the soap trick, powder trick, and I even used a smoke machine to try and find a leak. I cannot find one. Has anyone had a similar experience? The only thing I can think of is maybe the muffler cannot flow good enough and the noise is some type of backup or maybe there is a leak and for some reason I cannot find it?